Deciphering the Genetic Basis of Congenital Vertebral Malformations Through a Stepwise Diagnostic Approach.

Congenital vertebral malformations (CVMs), affecting approximately 0.5-1 per 1000 live births, occur either in an isolated form or as part of syndromic disorders. Despite the identification of numerous causative genes for CVMs, the molecular etiology of most cases remains unknown. In this study, we applied a three-tiered diagnostic approach (chromosomal microarray analysis, followed by custom gene panel analysis, and exome/genome sequencing) in a cohort of 34 patients with CVMs. We achieved a 12% diagnostic success rate, identifying a deletion upstream of SOX9 and pathogenic or likely pathogenic variants in FLNB and KMT2D. Most pathogenic variants were detected by exome or genome sequencing, while earlier-tier analyses yielded limited results. We also identified two candidate genes, NSD2 and TBXT, that may contribute to the phenotype observed in our patients, but warrant future functional validation. Our work expands the molecular spectrum of CVMs and highlights the utility of comprehensive genomic testing for improving diagnosis and understanding of vertebral development disorders.